When sharpening the teeth on the chain of a chain saw, it is necessary that the teeth be sharpened at a precise angle. For example, when sharpening the teeth for cutting oak, the angle of the tooth should be approximately 35 degrees. If the chain saw is to be used for cutting pine, then it may be desired to have the cutting edge of the teeth at a different angle. When these teeth are being sharpened by hand, it is difficult to stroke the front edge of the tooth with a file at precisely the same angle each time without some guide means.
There have been many attempts to provide guides for sharpening the teeth of a chain saw; however, they are normally complicated attachments that are relatively expensive and require a certain amount of time to install for use. Examples of some such sharpening devices are disclosed in U.S. Pat. Nos. 3,744,349; 4,062,253; 2,859,642; 3,670,600; 3,465,795; and 2,729,987.